Determination of Ångström's turbidity coefficient from direct total solar irradiance measurements

Abstract A method of determining Angstrom's turbidity coefficient from the measured total (broadband) direct normal solar irradiance is described here. This direct normal irradiance can be expressed in terms of the individual transmittances of the various atmospheric attenuators, such as ozone layer thickness, precipitable water vapor thickness, and α and β of the Angstrom's turbidity formula. From the resulting parameterization equation, an explicit expression for β is obtained. By assigning a fixed value to α, the value of β is determined. Use of this method is demonstrated with data from Ajaccio (France), a mediterranean coastal station.